documentation corrections
add metrics test dependency
helper to start up a test socket server
no logging unless debug mode is set
changed write_frame to create a combined buffer before writing out to the socket (benchmarking shows it is faster)
adding BufferOverflowError which is thrown when the max_buffer_size is passed.
Added check to avoid multiple registers on the drain event.  Also added two levels of buffer checking so that first stage is the pause/resume events and the second stage is rejecting the write.